Colonization by arbuscular mycorrhizal and fine endophytic fungi in herbaceous vegetation in the Canadian High Arctic

The occurrence of arbuscular mycorrhizal (AM) fungi was surveyed along a latitudinal gradient in Arctic Canada including Banks Island (73degreesN), Devon Island (74degreesN), Ellesmere Island (76degreesN), and the Magnetic North Pole at Ellef Ringnes Island (78degreesN). At Banks Island, AM fungi were present and colonized at a high intensity in all specimens of Potentilla hookeriana Lehm. - Potentilla pulchella R.Br., Arnica angustifolia Vahl, and Erigeron uniflorus L. ssp. eriocephalus (Vahl ex Hornen.) Cronq. sampled. The soil collected under these plants showed a high inoculum potential when tested at greenhouse conditions using Plantago lanceolata L. as a bait plant. Occasional occurrence of AM fungi was recorded in Festuca hyperborea Holmen ex Frederiksen, Trisetum spicatum (L.) Richt., and Potentilla hookeriana - Potentilla pulchella at Devon Island. Despite the fact that potential AM plants are present, no AM was found at the two most northern sites, Ellesmere Island and Ellef Ringnes Island. There seems to be climatic or dispersal limitations to AM colonization at these northern sites. Fine endophytic fungi, formerly named Glomus tenue (Grenall) I.R. Hall, were recorded at all four sites, but most frequently at Banks Island. We thereby provide further evidence that fine endophytes are more frequent in harsh climatic conditions than AM fungi. There was a relatively high proportion of nonmycorrhizal plant species at all sites, and this proportion increased towards the north.